German Published Patent Application No. 197 19 764 discusses a motor vehicle radar sensor that includes an antenna system which includes a focusing arrangement and at least two first antenna feeds that are arranged along a first straight line and form a first array of antenna feeds, in which is present at least one additional antenna feed which is arranged in such a manner that at least one additional array of antenna feeds is formed along an additional straight line, this additional array being capable of being laid out congruent to the first array by rotation about a hypothetical point of rotation M. This system provides a plurality of monostatic antenna feeds, each of which is used for transmitting as well as for receiving.
German Published Patent Application No. 197 31 085 discusses a device for transmitting and receiving radar waves, in particular for a range sensor. At least one antenna element is provided there, to which signals to be transmitted may be supplied and from which signals received may be picked up, the antennas being configured for the transmission of circularly polarized radar waves. The signals to be transmitted are supplied to at least one side of the antenna element in such a manner that they are radiated in a first plane of polarization. The signals received are picked up by the antenna at a second plane of polarization, which is orthogonal to the first plane of polarization. This system is also a monostatic transceiver system.